6 volt coil

[capt den]

i have a 6 volt coil that was on a greymarine boat engine, also a flathead 6 cylinder. is there a way to know if this coil will work on my 1954 265 engine without actually putting it on the car? i do not need a coil at this time, but it could be a spare if it will do the job. it is from 1958.     capt den 

[Plymouthy Adams]

read the primary coil winding for proper impedance.....

[capt den]

i have no idea what those numbers should be, guess i will read the one in the car and compare it to the other. not even sure how to do that.    capt den

[allbizz49]

Install it on your car and turn the key.

[chrysler1941]

12 hours ago, capt den said:

i have no idea what those numbers should be, guess i will read the one in the car and compare it to the other. not even sure how to do that.    capt den

If it's 6 cyl, impedance should be ok. It's different for an 8.

[Sniper]

number of cylinders has no bearing in coil resistance/impedance.

 

The impedance of a coil is essentially irrelevant for our purposes.  We aren't designing coils here.  All you need to worry about is using an external resistor if the coil calls for it and in a 6v system with a coil designed for that system it's not likely to be called for. 

 

If you want to know more

 

https://www.hemmings.com/stories/article/primary-ignition-resistance

[Adam H P15 D30]

I don't know what the actual impedance of a 6v coil is, MOST 12v canister coils are around 1.5 ohms.  When measuring, the important thing to look for is an actual value.  if the primary circuit or secondary circuit is open, the coil is bad.

[Sniper]

That sounds like the primary resistance, secondary will be in the kilo ohms range and both will vary.

 

Sometimes you can find the specs online.

 

The Standard Blue Streak UC14 coil, spec'd for a 51 Plymouth, calls for 3.25-3.50 primary 7700-9500 secondary, 27kv output.

 

Whereas, the Standard Blue Streak UC12, spec'd for a 74 Dart and what I used for my 12v conversion spec'd out at 1.4 ohms primary and 9,460 ohms secondary.  This one requires a ballast resistor to control current thru the points.

 

 

[chrysler1941]

1 hour ago, Sniper said:

If you want to know more

 

https://www.hemmings.com/stories/article/primary-ignition-resistance

I think you posted a wrong link.

Impedance has absolutely nothing to do with 12 v coils with ballast resistors

[Plymouthy Adams]

The first line in that article shows the writer bias and ignorance.....

[chrysler1941]

Typical 6 cylinder coils are around 3-3.5 Ohms

Typical 8 cylinder around 1.5 ohms

 

This why 6 and 8 cylinder Chrysler have two different part numbers.

[capt den]

i will try reading it today. thanks

[Sniper]

You forget that 12v coils with less primary impedance have a ballast resistor that adds the missing impedance, you must take the entire circuit into account.  Something a 6v setup does not have.  Which is why I REPEATED have stated you need to run the ballast resistor if the coil requires one.  

 

Why does a 12v coil have different internal impedance? Because with the increase of input voltage you need to rewind the coil to maintain the output spark.  If 27kv is the target output then with 12v in you need a 2250:1 step up, at 6v input you need to double that.  This will change impedance, period, and explains why a 6v coil has almost double the impedance of a 12v coil.  With the lesser impedance of a 12v coil the current thru the points goes up and a ballast is added to limit current thru the points so they don't burn up.  Some other brands add that needed resistance/impedance into the coil design, others have a resistance wire feeding the coil, Mopar used a ballast resistor. 

 

46 minutes ago, chrysler1941 said:

Typical 6 cylinder coils are around 3-3.5 Ohms

Typical 8 cylinder around 1.5 ohms

 

This would be accurate if it said 6v and 12v vice 6 cylinder and 8 cylinder.  As for why they may have different part numbers, any number of things, such as physical dimensions of the coil being different, terminals being different, heck the color of the coil can be a difference. 

[chrysler1941]

OP is about 6 volt coil so I don't understand why you write about 12v DC ballast resistors.

Impedance is AC resistance. It's a completely different matter.

6 and 8 cylinder coils have different impedance due to transformer coil saturation time. 8 lobes gives less time than 6.

 

 

[T120]

2 hours ago, Plymouthy Adams said:

The first line in that article shows the writer bias and ignorance.....

We'll just ignore Chrysler used it in 1972 .?

[Sniper]

7 minutes ago, T120 said:

We'll just ignore Chrysler used it in 1972 .?

 

I think it's how you choose to interpret the statement "The ignition distributor and breaker points were the mainstay in the industry until the 1975 model year automobiles were introduced."

 

AMC, Ford and GM didn't go to standard equipment electronic ignition till 75 and at the at point, lol, the US makers were all done with points in the US.  So it can be said that until 75 points were a mainstay, meaning in common use.  It doesn't mean no one used electronic ignition before 75.  There were optional EI systems available from all of them prior to 73 in Chrysler's case, or 75 for the rest of them.

[kencombs]

The deciding factor when choosing a coil is current flow.   As long as the current is kept below 4 amps, the point life will be satisfactory. I actually prefer to get to 3.5 for optimum life.  Measure the current and resistance and use Ohm's law to determine the real answer.

 

Impedance is normally used when discussing AC circuits, resistance is commonly used when discussing DC .  I don't own a meter that measures impedance, nor do I remember the math to get there with known resistance etc.

 

The difference in the coil marking, 12v vs 6v is the need for an external resistor or not, when used on a 12v  system.  A lot of 12v systems in the 50s and 60s used a 6v coil, with a series resistor to control the amperage.

 

 

[capt den]

i checked the ohms and the coil on the car read about 2.5 while the one from the greymarine enginet 3.5. seems like the one from the boat engine would be better for my car. might just swap them and see if there is any noticeable diference.   capt den

[Plymouthy Adams]

if you zeroed the ohm meter...your original is a bit high...the 3.5 screams internal resistor coil and will be useful only if you are 12 volt and not using a ballast....

[chrysler1941]

So, after some research I found some more documentation to support my statements.

 

First of all, this thread is about 6-volt coil, so all info regarding ballast resistors is irrelevant.

 

Attached page from 1947 Auto-Lite.

Highlighted are coil for 8 cylinders. They differ from 6 cylinder. Why is not known. Could be size or shape or bracketry.

 

Viewing a military ordinance document regarding current test procedure, clearly showing the exact same coil models. Both 6-volt coils, model IG and CE have different current draw. Why? Ohms law tells us it due to difference in coil winding.

 

This is how they did it the 40s.  Are 50’s 6 volt coils wound for a both 6 and 8? Any Documentation?

 

Attached, just for fun, page from Pretronix coil data. These are produced today. And what do you know, there are different coils for 6 and 8 cylinders, for both 6 and 12 volts.

Edited October 13, 2021 by chrysler1941

[Tom Skinner]

Gent,

I do not pretend to know anything about Volts Amps or Ohms. My question is with a Simpson Tube Volt Meter 1960's Style exactly how do I test my Coil for Ohms?

I zeroed out my Scale on my Meter it has a new battery 1.5 Volt I believe. So walk me through where to put the Black and Red Leads and whether I should have the ignition key on or off etc. I want to check my new 6 Volt Coil for 3-3.5 Ohms as instructed above. Basically I ask exactly how.

Thanks!

Tom

[Sniper]

4 hours ago, chrysler1941 said:

So, after some research I found some more documentation to support my statements.

 

First of all, this thread is about 6-volt coil, so all info regarding ballast resistors is irrelevant.

 

Attached page from 1947 Auto-Lite.

Highlighted are coil for 8 cylinders. They differ from 6 cylinder. Why is not known. Could be size or shape or bracketry.

 

Viewing a military ordinance document regarding current test procedure, clearly showing the exact same coil models. Both 6-volt coils, model IG and CE have different current draw. Why? Ohms law tells us it due to difference in coil winding.

 

This is how they did it the 40s.  Are 50’s 6 volt coils wound for a both 6 and 8? Any Documentation?

 

Attached, just for fun, page from Pretronix coil data. These are produced today. And what do you know, there are different coils for 6 and 8 cylinders, for both 6 and 12 volts.

 

Might want to rethink using Pertronix as any sort of authoritative source.  They list the 40011, 40001 and 40111 coils as working for both the 8 cylinder 12v setup AND the 4/6 cylinder 6v setup.  Pretty sure that's wrong and if not tends to undercut your theory.

[Sniper]

12 minutes ago, Tom Skinner said:

Gent,

I do not pretend to know anything about Volts Amps or Ohms. My question is with a Simpson Tube Volt Meter 1960's Style exactly how do I test my Coil for Ohms?

I zeroed out my Scale on my Meter it has a new battery 1.5 Volt I believe. So walk me through where to put the Black and Red Leads and whether I should have the ignition key on or off etc. I want to check my new 6 Volt Coil for 3-3.5 Ohms as instructed above. Basically I ask exactly how.

Thanks!

Tom

 

The primary and secondary windings of a coil share one terminal, same one that is hooked to the points.  Which is why miswiring the coil is a bad idea.

 

To measure an ignition coils resistance you clip the black wire to whatever terminal is normally connected to the points (first unwire anything wired to the coil, label your connections before removing).  In a positive ground system that would be the small threaded terminal labeled +.  This connection will remain connected when measuring both windings.

 

To measure the primary winding resistance connect the red lead to the coil - terminal, for resistance measuring polarity of the meter connections is really irrelevant.  Write this down.

 

To measure the secondary winding resistance connect the red lead to the coil plug wire terminal, for resistance measuring polarity of the meter connections is really irrelevant.  Write this down.

 

Done, remove meter connections, reconnect stock wiring you removed in earlier.

 

 

 

[Tom Skinner]

Sniper,

Thank you!

I will try this first thing tomorrow.

Tom

[chrysler1941]

6 hours ago, Sniper said:

Might want to rethink using Pertronix as any sort of authoritative source.  They list the 40011, 40001 and 40111 coils as working for both the 8 cylinder 12v setup AND the 4/6 cylinder 6v setup.  Pretty sure that's wrong and if not tends to undercut your theory.

The Auto-Lite and Chrysler sheets is my authoritative. 

Pertronix data was for fun and info as stated.  

 

40011,40001 and 40111 coils are 1.5 Ohms used for 6 cylinder 6 volts.

45011,45001 and 45111 coils are 0.6 Ohms used for 8 cylinder 6 volts.

You can't mix voltages

 

 

Edited October 14, 2021 by chrysler1941